LANDSYSTEMS ANALYSIS OF SURFICIAL GLACIAL DEPOSITS IN SIMCOE COUNTY, SOUTHERN ONTARIO

Chapman and Putnam (1984) developed a landscape classification framework for southern Ontario grouping Quaternary glacial terrain into physiographic regions, based on surface morphology and dominant sediment type. Modern surficial mapping investigations combine sedimentology with high-resolution imagery and surface models, allowing further refinement of physiographic regions into their component landsystems – geographic areas of landforms and sediments formed in a suite of related environments.

In Simcoe County, Ontario, 7 physiographic regions fall within four broader physiographic domains – the Niagara Escarpment, Simcoe uplands, Oak Ridges Moraine, and Simcoe lowlands. Within these domains, 14 distinct landsystems are mapped. The Niagara Escarpment domain comprises a bedrock escarpment, hummocky ridges, streamlined terrain, low-relief uplands, gravel benches, flat-floored channels, and V-shaped valleys. The Simcoe uplands are composed of streamlined terrain, low-relief uplands, transverse ridges and sand and gravel fills, flat-lying plains and scarps, and erosional amphitheatres. Hummocky terrain and V-shaped valleys are observed in the Oak Ridges Moraine. The Simcoe lowlands contain streamlined terrain, flat-lying plains and scarps, arcuate ridges and platforms, low-lying basins, and clustered ridges. The morphology, composition, spatial and stratigraphic relationships of landsystems assists in analysis of spatiotemporal changes in glacial environments and highlights the interrelationship of processes that operated across modern physiographic boundaries. This approach has helped to identify the nature and relative timing of major events that occurred since the last glacial maximum, including: i) the timing of till drumlinization relative to lowland valley formation; ii) the relationship between ice marginal positions, meltwater channels, and glacial lake shoreline evolution; iii) nature of ice retreat following deposition of large interlobate moraines.